EMC - Cardiologie-Angéiologie最新文献

Thyroid hormone directly affects the heart and the peripheral vascular system. It increases myocardial inotropy and heart rate and dilate peripheral arteries to increase cardiac output. Triiodothyronine (T₃) enters the cardiac monocytes, and binds to nuclear T₃ receptors. The complex then binds to thyroid hormone response elements of the genes for several cell constituents and regulates transcription of these genes, including those for Ca ²⁺ -ATPase and phospholamban in the sarcoplasmic reticulum, myosin, β-adrenergic receptors, adenylyl cyclase, guanine-nucleotide– binding proteins, Na⁺/Ca²⁺ exchanger, Na⁺/K⁺ – ATPase, and voltage-gated potassium channels. Non nuclear T₃ actions on ion channels for sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺) ions represent an alternative way of action for thyroid hormone. Many electrocardiographic abnormalities have been described in hyperthyroidism including sinus tachycardia, atrial and ventricular extrasystoles, atrial fibrillation (AF), atrioventricular block and ventricular repolarisation abnormalities. AF is common in patients with hyperthyroidism, which predisposes to embolic events. Subclinical hyperthyroidism is associated with increased heart rate atrial arrhythmias, increased left ventricular mass impaired ventricular relaxation and reduced exercise performance. Overt hypothyroidism increases of coronary disease, pericardial effusion, systolic hypertension, myocardiopathy and congestive heart failure. Subclinical hypothyroidism is associated with impaired left ventricular diastolic dysfunction at rest, with systolic dysfunction in case of stress; the risk for atherosclerosis and myocardial infarction is increased.

Isolated ventricular septal defect (VSD) is the most common congenital cardiac malformation. VSD is also the most frequent defect associated to others congenital cardiovascular malformations. The numerous anatomic varieties of VSD explain the great variability of the clinical features and the differences in the natural history. With echocardiography and colour Doppler, the diagnosis of VSD is easier and more accurate than previously; so, pre-operative catheterization is no longer needed in most of the cases. The course of VSDs, depending on their size and location, may be early predicted in analysing their anatomic aspect by repeated echocardiography Doppler during the first months of life. Most of them become proportionally smaller with time and, finally, close spontaneously during infancy, childhood or adolescence. Few VSDs need early surgical closure to avoid complications of a large left-to-right shunt, such as cardiac failure and pulmonary hypertension secondary to a severe damage of pulmonary arteries. This management prevents Eisenmenger's syndrome, an irreversible situation corresponding to an inversion of the shunt in relation to high pulmonary vascular resistance. When VSD persists in adults, others complications such as infective endocarditis and aortic regurgitation may occur; therefore, strict surveillance and antibiotic prophylaxis are recommended in concerned patients. Owing to the improvement of cardiac surgery in low weight infants, the surgical closure of large VSD in infancy gives currently excellent results. Apical muscular VSD and multiple muscular VSD still present a particular surgical challenge: today, their closure may be achieved using a ventricular septal device during surgery or interventional catheterization. In this article, only isolated VSDs will be considered. Indeed, VSDs that constitute an integral part of a more complex malformation, such as the “tetralogie de Fallot” or complete atrio-ventricular defect, have a different presentation and require a specific treatment. Persistent VSD after correction of another cardiac malformation (aortic coarctation, transposition of great arteries, etc .) may be assimilated to isolated VSDs because they have usually similar clinical features and outcome.

The surgical management of congenital heart diseases in adult patients is characterized by the diversity of the anatomo-clinical situations and the difficulty of the specific surgical techniques. The pre-surgery evaluation is of great importance. The cardiac lesions encountered are often suitable for biventricular repair; however, there are also previously repaired hearts that require new surgical intervention due to the deterioration of the initial result. Encouraging results of surgery are observed, in terms of mortality and quality of life as well.

All guidelines on the management of arterial hypertension stress on the lifestyle measures have demonstrated their efficacy on blood pressure reduction. Although their effect on the cardiovascular risk remains hypothetical, they are, or should be, instituted in every hypertensive or pre-hypertensive subject. The five lifestyle measures that are widely agreed as lowering blood pressure are: 1) weight reduction, 2) reduction of excessive alcohol intake, 3) physical exercise, 4) reduction of salt intake and 5) augmentation of fruit and vegetable intakes and reduction of saturated and total fat intakes. It is reasonable to consider that these lifestyle modifications are, at best, additive to pharmacological treatment. As such modifications are difficult to institute and maintain in individuals, health education and public health campaigns should help practitioners in better controlling blood pressure in the general population.